Digestion Begins at the Tip of the Nose
In horse feeding, there is hardly a more complex topic than the digestive system itself. Most horse owners probably don't know that the lips and teeth, which are responsible for food intake, are already part of the digestive tract. The duration and intensity of chewing depend, among other things, on the structural content of the feed. Therefore, concentrate feed is eaten significantly faster than roughage like hay. While chewing, the horse produces saliva, which is mixed with the food mash. A horse can even produce up to 5 kg of saliva per 100 kg of body weight per day! [1]
Horses Cannot Vomit
The chewed and salivated food travels through the esophagus into the horse's stomach. Unlike humans, horses cannot vomit. This is due to a strong muscle at the entrance of the stomach that prevents the reflux of food into the esophagus. However, this also means that gastric overload in horses is extremely dangerous. The stomach, with a capacity of about 15-20 liters, is very small in relation to the horse's body size. [2] For this and other reasons, frequent, smaller meals are advisable for horses. A maximum concentrate amount of 0.3 kg per 100 kg of body weight per meal is recommended. [3]
Horses have a single-chambered, compound stomach. This means that the stomach consists of two parts: the glandular and the non-glandular part. During a gastroscopy, this separation can even be clearly seen visually, as the two parts are actually visibly separated by a boundary line (margo plicatus). [4] The two parts are also differently colored. While the non-glandular upper part of the stomach is white, the lower glandular part is reddish.
What About Gastric Ulcers?
Gastric ulcers are often found precisely at the transition between the two parts. This is because the non-glandular part of the stomach is not designed to come into contact with stomach acid. As continuous grazers, horses constantly produce stomach acid, regardless of whether they are eating or not. Long feeding breaks (> 4 hours) can lead to an excess of acid. Stomach acid can therefore attack the sensitive non-glandular mucous membrane in the upper part of the stomach. As one can imagine, this is a very painful condition for horses. Stress of any kind, excessive amounts of concentrate feed, or pain can also lead to gastric ulcers. Symptoms of gastritis or gastric ulcers are extremely varied and are therefore sometimes not recognized. As a preventive measure, we recommend providing horses with sufficient roughage, meaning at least 1.5 kg of hay per 100 kg of body weight. Feeding breaks should also ideally not last longer than 4 hours. For horses with sensitive stomachs, gastric protection can often be supplemented. Mucus-forming ingredients additionally line the stomach and protect the mucous membrane from aggressive stomach acid. Nevertheless, with gastric ulcers, the cause should be investigated and the trigger eliminated if possible.
Horses Do Not Have a Gallbladder
From the stomach, the pre-digested food enters the intestine. The horse's intestine can be up to 40 m long, depending on the size of the horse. The small intestine accounts for a large part of this, about 25 m. In the small intestine, for example, the digestion of starch, fat, and proteins takes place. A special feature of horses is that they do not have a gallbladder. In this case, bile acids are continuously produced by the liver and, among other things, neutralize stomach acid. In addition, bile acids support fat digestion.
Nothing Works for a Horse Without the Cecum!
The horse's large intestine consists of the cecum, the large and small colon, and the rectum. Compared to other species, the horse's cecum, at about one meter in length, is very large and essential in its function! Without the cecum, a horse could not survive, quite unlike a human. The cecum and colon are the two fermentation chambers of the digestive tract. The horse's large intestine is primarily responsible for crude fiber digestion. But also B-complex vitamins, vitamin C, and vitamin K are formed and absorbed by the large intestine bacteria. Therefore, the body is generally not dependent on their external supply. However, digestive problems or a disturbed large intestine flora can lead to an imbalance of the intestinal bacteria and possibly to deficiency symptoms. Causes of such an imbalance in the large intestine flora can also be, for example, antibiotics or certain medications. Stress or spoiled feed can also be triggers for dysbiosis in the large intestine.
If there is suspicion of an imbalance in the large intestine flora, it may therefore be useful to supplement, for example, B vitamins. The feeding of live yeast Saccharomyces cerevisiae can also support the microorganisms in the large intestine and restore balance.
Dysbiosis Can Also Affect Stool Consistency
In the large intestine, the reabsorption of water and fluid also takes place. An imbalance in the intestine can, among other things, impair water absorption in the intestine, which can lead to diarrhea and loose stools. There are various, very different causes for loose stools and diarrhea. However, we generally advise keeping an eye on the gut flora in cases of diarrhea and loose stools. Supplements with water-binding properties, which improve stool consistency, can be fed as a supportive measure. Products containing pectin, kaolin, or psyllium husks are suitable here. Pectin also has positive effects on the gastric mucosa.
[1] Meyer, H. & Coenen, M. (2014) Pferdefütterung (5. Auflage) Enke Verlag, Stuttgart
[2] Meyer, H. & Coenen, M. (2014) Pferdefütterung (5. Auflage) Enke Verlag, Stuttgart
[3] FN (2017) Grundwissen zur Haltung, Fütterung, Gesundheit und Zucht, Richtlinien für Reiten und Fahren Band 4, FNverlag der Deutschen Reiterlichen Vereinigung GmbH
[4] Nickel, R. & Schummer A. & Seiferle E. (1999) Lehrbuch der Anatomie der Haustiere. Band 2, 8. Auflage, Parey Verlag, Berlin & May, A. & Venner, M. & Cavicchioli, E. & Gehlen, H. (2012) Magenerkrankungen des Pferdes – Diagnostik und Therapie, Pferdeheilkunde 28 (2012) 4 (Juli/August) 388-405
